Vertical steam generator with a central downcomer



Jan. 17, 1967 J. w ALDEN, JR

VERTICAL STEAM GENERATOR WITH A CENTRAL DOWNCOMER Filed Dec. 50, 1964 2 Sheets-Sheet l JOHN W ALDEN JR.

INVENTOR J 6' av W M ATTORNEY Jan. 17, 1967 'J. w. ALDEN, JR 3,298,358

VERTIICAL STEAM GENERATOR WITH A CENTRAL DOWNCOMER Filed Dec. 30, 1964 2 Sheets-Sheet 2 FIG. 6 FIG. 8

dabw W ALD'N JR.

/N VEN TOR W, 1 cow ATTORNEY heating surface. 7 present unit are disposed such that the inlet ends and the 3,298,358 VERTICAL STEAM GENERATORWITH A CENTRAL DOWNCOMER John W. Alden, Jr., Chattanooga, Tenn., assignor to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Dec. 30, 1964, Ser. No. 422,298 16 Claims. (Cl. 122.-34)

The present invention relates generally to, a vapor generating unit of the shell and tube type in which heat is supplied by a heating fluid. flowing through the tubes. More particularly, it relates to a shell and tube type vapor generating unit in which the tubes that conduct the heating fluid are U-tubes. that are, arranged in separate tube bundles with the tube bundles being located in circumferentially spaced positions about a central downcomer to form an annular vapor generation chamber.

In modern-day industries, such, as petroleum refining, chemical manufacture and nuclear. energy, there are available high temperature fluids from which heat. may be extracted for useful purposes. The present invention is directed to a vapor generatingunit which is operable to extract heat from such high temperature fluids for'the purpose of transforming a vaporizable liquid into vapor. The unit isspecifically arranged to occupy a minimum amount of space While transferring large. quantities of heat. Moreover, the tubes that conduct the heating fluid are arranged in such a. manner as to provide a large amount of heating surface within a minimum. amount of space relative toheretofore known arrangements there-- by enhancing the over-all economy of the unit. It is contemplated by this invention to arrange the U-tubes that provide the means for conducting heating fluid in separate groups or tube bundles that are arranged about a centrally located downcomer reservoir-that is formed by plate means that coact with the wall ofthe vessel to form an interior downcomer reservoir and an exterior vapor generation chamber. In units of heretofore known design having conventionally arrangedtube bundles it was impossible to employ a central downcomer reservoir without-having to eliminate a wide swath of tubes to accom-- modate the plate means that form the reservoir. By means of the invention the tubes of the unit areso arranged as to.conveniently provide for the mounting of such plate means without having to eliminate useful Moreover, the tube bundles in the outlet ends of the tubes of adjacent tube bundles are positioned adjacent one another such that the heating fluid chamber can be conveniently compartmentized in a manner as to obtain efficient separation of hot heating fluid and spent heating fluid within the chamber.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had-to the. aecompanyingdrawings and descriptive matter wherein is described and illustrated the preferredernbodirnents of the invention- In the drawings:

FIGURE 1 is a vertical side section of oneernbodiment of the present invention;

FIGURE 2 is a plan section taken along line 22 of FIGURE 1;

FIGURE 3 is a section taken alongline 33 'of FIG- URE 1;

fied form of heating fluid chamber;

United States Patent vtubes 34 that substantially fill this chamber.

3,298,358 Patented Jan. 17, 1967 ice FIGURE 5 is a section taken along line 5-5 of FIGURE 4;

FIGURE 6 is a partial side section of another embodimentof the heating fluid chamber;

FIGURE 7 is a plan section taken along line 7-7 of FIGURE 6;

FIGURE 8 is a partial vertical side section of yet another embodiment of the heating fluid chamber; and

FIGURE 9 is a plan section taken along line 99 of FIGURE 8.

The vapor generating unit 10 comprises a vertically elongated pressure vessel including a cylindrical shell 12' and an integral vapor drum 14. The vessel has an upper disc-shaped head 16 and a lower hemispherical head 18 closing. the ends thereof. During normal operation of the vapor generating unit a body of liquid occupies a portion of the vessel establishing a liquid level 20 which forms an upper vapor space 22 and a lower liquid space 24. Plate means including vertically disposed, rectangularly arranged. baflle plates 26 in conjunction with the walls of the shell 12 coact to form an interior downcomer reservoir 28 and an exterior vapor generation chamber 30. As. shown in FIGURE 3 the rectangularly disposed baflle plates 26 can be replaced by a cylindrical baiflle 26 without departing from the inventive concept. Laterally disposed support plates 32 extend between the vessel wall and the plates 26 to support separator units 52. The. downcomer reservoir 28 is vertically elongated cross sectional dimension ofthe vessel shell 12. Between it and the wall of the shell 12 is located the vapor generation chamber 30 that is substantially annular in shape and which houses a plurality of heating fluid conducting The baffle plates 26 extend to substantially the bottom of the vapor generation chamber 30 but are spaced therefrom so as to provide fluid communication between the downcomer reservoir 28 and'the vapor generation chamber.

A tube sheet 36 extends transversely across the bottom of the vapor generation chamber 30 integral with the wall of the shell 12 andforms a heating fluid chamber 38 in the bottom of the unit. Thetubes 34 whose ends attach to the tube sheet 36 are generally U-shaped tubes that are arranged in rows lying in parallel planes that form separate tube bundles 40, 42, 44 and 46 with each tube bundle being shaped as shown best in FIGURES 2 and 3 as.atruncated cylindrical segment and occupying substantially one quadrant of the vapor generation chamber 30. As also shown in FIGURE 2 the tube bundles-40, 42, 44 and.46 are so arranged that the inlet ends 48 and the outlet ends 50 of all of the tubes in each tube bundle are arranged in groups with ends of tubes in adjacent tube bundles being grouped together to facilitate separation of incoming and outgoing heating fluid in the chamber 38.

Such an arrangement of tubes has several manifest advantages. First of all, by positioning the tubes 34 in separate tube bundles that surround the central downcomer reservoir 28there is achieved the economy of space that results from the elimination of the removal of a wide swath of U-tubes that would otherwise have to be removed in order to employ a central downcomer reservoir with a conventionaltube bundle. With this arrangement therefore a greater amount of heating surface can be obtained from a unit of a given capacity. Secondly, in arranging the tube bundles such that the hotter inlet ends of all of the tubes in the unit are divided so as to occupy opposed quadrants of the-vessel and likewise with the cooler outlet ends there is provided a more uniform generation of vapor throughout the transverse section of the unit that gives riseto more efficient use of separators that are employed to separate the vapor-liquid mixture generated in the vapor generation chamber.

Within the vapor drum 14 that encloses the vapor space Y 22 is positioned a plurality of centrifugal separators 52 of known construction that are operable to separate the vapor and liquid components of the mixture generated in the vapor generation chamber 30. The separators 52 are mounted in a double row atop the lateral support plates 32 in circumferentially spaced relation about the batfle plates 32 from whence it flows into the downcomer reservoir 28. The vapor released into vapor space 22 is caused to flow through a screen dryer 62 that extends across the vapor outlet 64 where any entrained moisture can finally be removed prior to the vapors passing out through the vapor outlet 64 to a point of use.

The makeup vaporizable liquid for the unit enters by the inlet pipe 66 that connects with nozzle 68 and directs the incoming liquid into the downcomer reservoir 28. Liquid removed from the vapor by the secreen dryer 62 is discharged into the reservoir 28 by means of a discharge tube 70.

As shown in FIGURE 1 the tube sheet 36 extends across the lower portion of the vessel and forms, along with the lower closure head 18, the heating fluid chamber 38 that serves as the inlet and outlet manifold for the U-tubes 34. A centrally located cylindrical conduit 72 aligned with the plate means 26 extends between, and attaches to, the tube sheet 36 and the inner surface of the closure head 18. The conduit 72 is adapted to conduct heating fluid from source (not shown) to the heating fluid chamber 38 connecting to the source through an inlet nozzle 74. Openings 76 in the conduit wall effect communication between the conduit and heating fluid compartments hereinafter described. The conduit 72 is further effective to strengthen the tube sheet 36 intermediate its peripheral edge in that it serves as a vertical staying device between the tube sheet 36 and the closure head 18. By reason of this the required tube sheet thickness can be materially reduced.

The heating fluid chamber 38 is divided into fluid compartments by means of a plurality of vertically disposed, radially arranged divider plates 73 that are attached to the surface of the lower closure head 18, the tube sheet 36 and the central conduit 72 thereby dividing the heating medium chamber into alternating heating fluid inlet and outlet compartments 78 and 80, respectively, that serve as manifold devices for the inlet and outlet ends of the U-tubes. The central conduit openings 76 communicate with the heating fluid inlet compartments 78 for the purpose of supplying these compartments and the in-.

let ends 48 of the U-tubes 34 with heating fluid. The fluid that flows through the tubes of the tube bundles is deposited into the heating fluid outlet compartments 80 that communicate with the outlet ends 50 of the U- tubes. A cross-over pipe 82 penetrates the central conduit 72 and communicates at its end with the opposed outlet compartments 80 to direct the outlet fluid to a single compartment from whence it can be removed through the heating fluid outlet nozzle 84.

In operation, feedwater is introduced to the unit through the feedwater nozzle 68 and feedwater pipe 66 and is discharged into the downcomer reservoir 28 from whence it flows into the vapor generation chamber 30 and there establishes a normal operating level 20. At the same time heating fluid is supplied from a source (not shown) through the inlet nozzle 74 that connects with the cylindrical conduit 72 and passes through openings 76 therein into the opposed heating fluid inlet compartments 78 from "whence it"flows'through' the tubes 34'of the tube bundles 40, 42, 44 and 46. After flowing through the tube bundles the heating fluid is discharged into the alternate heating fluid outlet compartments 80 from whence it is removed through the cross-over pipe 82 and outlet nozzle 84, thereby recirculating through the source. The vaporizable liquid deposited into the vapor generation chamber 30 extracts heat from the heating fluid flowing through the U-tubes 34 and is transformed into a liquidvap-or mixture that flows through openings 56 in the plates 32 into vapor-liquid separators 52. The separators 52 are arranged to deposit the vapor removed from the mixture into the vapor space 22 and the liquid therefrom into the downcomer reservoir 28 whence it is recirculated through the unit. The removed vaporis caused to flow through the screen dryer 62 where any mixture not removed by the separators is eliminated prior to the vapors passing through the outlet nozzle 64 to be delivered to its point of use.

In FIGURES 4 and 5 is shown another embodiment of the present invention wherein the heating fluid chamber "38' is compartmentized by means of vertically disposed,

radially arranged plates 73' and a pair of horizontally disposed plates 86 that attach to the wall ofthe closure head 18 and to the central conduit 72. Lateral plates 86 extend between alternate spans formed by the plates 73 to form the heating fluid inlet compartments 78. Openings 76 are provided in the central conduit communicating with the heating fluid inlet chambers so as to supply heating fluid thereto. From these compartments 78' the heating fluid is caused to flow through the U- tubes 34 in a manner similar to that "of the FIGURE 1 arrangement and is discharged from the outlet ends 50 of the tubes into the single heating'fluid outlet compartment 80' that occupies the remainder of the chamber from whence it may flow from the chamber through the heating fluid outlet nozzle 84.

In the embodiment shown in FIGURES 6 and 7 the heating fluid chamber is divided into quadrants by means of baflle plates 73" similar to those shown in the FIGURE 1 embodiment. Again, openings 76 in the central conduit 72 establish fluid communication between the heating fluid inlet compartments78" for the passage of heating fluid thereto. The alternate compartments 80 are again those into which the heating fluid is discharged from the outlet ends 50 of the U-tubes 34. In this embodiment an outlet nozzle 84 communicates with each of the outlet compartments 80" for the removal of spent heating fluid from the unit.

In the embodiment shown in FIGURES 8 and 9, baflie plates 73" divide the heating fluid chamber 38 into alternate heating fluid inlet and outlet compartments 78" and 80" and individual inlet and outlet nozzles 90 and 92 communicate with each of the compartments whereby heating fluid is supplied to the inlet compartments 78" through nozzles 90 and removed from the outlet compartments 80" through nozzles 92. In this embodiment the central conduit 72 has a continuous surface and is employed as a manway for access to the vapor generation chamber 30. As shown the tube sheet 36 is provided with a central opening 94 that is closed by a cover 96 around which the upper end of the central conduit 72attaches for the purpose of permitting access from outside the unit to the vapor generator interior.

While in accordance with the provisions of the statutes, there has been illustrated and described specific forms of the invention, it is to be understood that changes may be made in the forms of the apparatus disclosed without departing from the spirit of the invention covered by the .5 space above a body of liquid therein; a vapor outlet from said vapor space; plate means coactingwiththe wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularlyshaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced therefrom to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means for supplying vaporizalble liquid to said downcomer reservoir; at least three separate tube bundles each comprising a group of vertically elongated U-tubes arrangedin rows lying in parallel planes, said tube bundles being located in circumferentially spaced positions about said plate means and substantially filling said vapor generation chamber; and heating fluid inlet and outlet means communicating with the tubes of said tubebundles for circulating heating fluid therethrough.

2. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space labove a bodylof liquidtherein; a vapor outlet from said vaporspaceg-plate means coactinglwith the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vessel generation spaced position about said :plate means and su-btantially filling said vapor generation chamber; and heating fluid inlet and outlet means communicating with the tubes of said tube bundlesfor circulatingheating fluid therethrough.

3. A vapor generator com-prisinga vertically elongated cylindrical vessel arranged to operatewith an upper vapor space aboveabodyof liquid therein; a vapor outlet from said vapor-space; plate means coacting .with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the. bottom of said vapor generation chamber butbeing spaced therefrom to establish fluid communicationbetween said downcomer reservoir and said vapor generation chamber; means for supplyingvaporizableliquid to said downcomer reservoir; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes arranged in rows lying in parallel planes and having upwardly disposed bends, said tube bundles being located in circumferentially spaced positions about said plate meanspand each occupying substantially onequadrant of said vapor generation chamber; and heating fluid inlet andoutlet means communicating with thetubes of said tube bundles for circulatingheating fluid therethrough.

4. A vapor .genera-t-orcomprlsmg a vertically elongated cylindrical vessel arrangedto operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; plate, means coac-ting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced therefrom to establish fluid communication between said downcomer reservoir, and said =vapor generation chamber; means for.

supplying vaporizable liquid to said downcomer reservoir;

a plurality of separate t'ube'bundles each comprising a spaced positions about said plate means and each having the shape of a truncated cylindrical segment occupying substantially one quadrant of said vapor generation chamber.

, 5. A vapor generator comprising'a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; plate means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir andan annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generationchamber but being spaced therefrom to establish fluid communication between saiddowncomer reservoir and said vapor generation chamber; a plurality of separate tube bundle each comprising a group of vertically elongated'U-tubes arranged'in rows lying in parallel planes and having upwardly disposed bends, said tube bundles being located in circumferentially spaced positions about said plate means and each having the shape of a truncated cylindrical segment with corresponding tubes in each tube bundle lying in rectangularly disposed planes; and heating fluid inlet and outlet means communicating with the tubes of said tube'bundles for circulating heating fluid therethrough.

6. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; plate means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means. for supplying vaporizable liquid to said downcomer reservoir; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U- tubes being arranged in rows lying inparallel planes and having upwardly disposed bends, said tube bundles being located in circumferentially spaced positions about said plate means and each occupying substantially one quadrant of said vapor generation chamber; means connecting the inletvends' and outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough; and heating fluid inlet and outlet means communicating with said heating fluid chamber.

7. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis-of said vessel forming a heating fluid chamber in the bottom thereof; plate means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an 'annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but i a being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means forsupplying vaporizable liquid to said downcomerreservoir; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U-tubes being arranged inrows lying in parallel planes and having upwardlydisposed bends, said tube bundles each having'the shape of a truncated cylindrical segment and being located in circumferentially spaced positions about said plate means; means connecting the inlet ends and outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough; and

' heating fluid inlet and outlet means communicating with said heating fluid chamber. a

8. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; plate means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; mean for supplying vaporiza'ble liquid to said downcomer reservoir; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U- tubes being arranged in rows lying in parallel planes and having upwardly disposed bends, said tube bundles each having the shape of a truncated cylindrical segment and being located in circumferentially spaced positions about said plate means with corresponding tubes in each tube bundle lying in rect-angularly disposed planes about said plate means; means connecting the inlet ends and outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough; and heating fluid inlet and outlet means communicating with said heating fluid chamber.

9. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; plate means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means for supplying vaporizable liquid to said downcomer reservoir; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U-tubes being arranged in rows lying in parallel planes and having upwardly disposed bends, said tube bundles each having the shape of a truncated cylindrical segment occupying substantially one quadrant of said vapor generation chamber; means connecting the inlet ends and outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough; and heating fluid inlet and outlet means communicating with said heating fluid chamber.

10. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; plate means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor genera-tion chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcomer'reservoir'and said vapor generation chamber; means for supplying vaporizable liquid to said downcomer reservoir; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said. tube sheet in cornmunication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U- tubes being arranged in rows lying'in'parallelplanes ends of adjacent tube-bundles for mutual parallel flow ofheating fluid therethrough; and heating fluid inlet and outlet means communicating with-said heating fluid chamber. v

11. A vapor generator comprising a'vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid'chamber in the bottom thereof; first plate means coacting with "the" Wall of said vessel to'form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said first plate means extending downwardly to substantially-the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means for supplying vaporizable liquid to said downcomer reservoir; vapor liquid separating means arranged to separate a vapor-liquid mixture received from said vapor generation chamber and for discharging separated liquid to said downcomer reservoir and vapor to said vapor space; second plate means extending between said first plate means and said vessel wall for supporting said separating means;

opening means in said second plate means communicating said separator means with said vapor generation chamber; a plurality of separate 'tube bundles each comprising a group of vertically elongated U-tubes attached to' said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U-tubes being arranged in rows lying in parallel planes and having upwardly disposed bends, said tube bundles being located in circumferentially spaced positions about said first plate means and each occupying substantially one quadrant of said vapor generation chamber; means connecting the inletends and the outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough, and heating fluid inlet and outlet means communicating with said heating fluid chamber.

12. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space;'.a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; first plate .means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamberv exterior of said reservoir, said first plate means extending downwardly to substantially the bottom of said vapor generation chamberbut being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means for supplying vaporizable liquid to said downcomer reservoir; vapor liquid separating means arranged to separate a vapor-liquid mixture received from said vapor generation chamber and for discharging separated liquid to said downcomer reservoir and vapor to said vapor space; second plate means extending between said first plate means and said vessel wall for supporting said separating means; opening means in said second plate means communicating vsaid separator means with said vapor generation chamber; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U-tubes being arranged in rows lying in parallel planes and having upwardly disposed bends, said tube bundles eachhaving the shape of a truncated cylindrical segment and being located in circumferentially spaced positions about said first plate means; means connecting the inlet ends and the outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough, and heating fluid inlet and outlet means communicating with said heating fluid chamber.

13. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; first plate means coacting with the wall of said vessel to form an interior, vertically elongated downcorner reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said first plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcorner reservoir and said vapor generation chamber; means for supplying vaporizable liquid to said downcorner reservoir; vapor liquid separating means arranged to separate a vapor-liquid mixture received from said vapor generation chamber and for discharging separated liquid to said downcorner reservoir and vapor to said vapor space; second plate means extending between said first plate means and said vessel Wall for supporting said separating means; opening means in said second plate means communicating said separator means with said vapor generation chamber; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluid therethrough, said U-tubes being arranged in rows lying in parallel planes and having upwardly disposed bends, said tube bundles each having the shape of a truncated cylindrical segment and being located in circumferentially spaced positions about said first plate means with corresponding tubes in each tube bundle lying in rectangularly disposed planes about said first plate means; means connecting the inlet ends and the outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough, and heating fluid inlet and outlet means communicating with said heating fluid chamber.

14. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; first plate means coacting with the wall of said vessel to form an interior, vertically elongated downcorner reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said first plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means for supplying vaporizable liquid to said downcorner reservoir; vapor liquid separating means arranged to separate a vapor-liquid mixture received from said vapor generation chamber and for discharging separated liquid to said downcorner reservoir and vapor to said vapor space; second plate means extending between said first plate means and said vessel wall for supporting said separating means; opening means in said second plate means communicating said separator meanswithsaid vapor generation chamber; a plurality of separate tube bundles each comprising a group of vertically elongated U-tubes attached to said tube sheet in communication with said heating fluid chamber and arranged for the circulation of heating fluidtherethrough, said U-tubes being arranged in rows lying in parallel planes and having upwardly. disposed bends, said tube bundles each having the shape of a truncated cylindrical segment occupying substantially one quadrant of said vapor generation chamber; means connecting the inlet ends and the, outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough, and heating fluid inlet and outlet means communicating with said heating fluid chamber.

15. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; first plate means coacting with the wall of said vessel to form an interior, vertically elongated downcomer reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said first plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcomer reservoir and said vapor generation chamber; means for supplying vaporizable liquid to said downcorner reservoir; vapor liquid separating means arranged to separate a vapor-liquid mixture received from said vapor generation chamber and for discharging separated liquid to said downcorner reser- I planes and having upwardly disposed bends, said tube bundles each having the shape of a truncated cylindrical segment occupying substantially one quadnant of said vapor generation chamber with corresponding tubes in each tube bundle lying in rectangularly disposed planes about said first plate means; means connecting the inlet ends and the outlet ends of adjacent tube bundles for mutual parallel flow of heating fluid therethrough, and heating fluid inlet and outlet means communicating with said heating fluid chamber.

16. A vapor generator comprising a vertically elongated cylindrical vessel arranged to operate with an upper vapor space above a body of liquid therein; upper and lower closure heads closing the ends of said vessel; a vapor outlet from said vapor space; a tube sheet disposed laterally of the axis of said vessel forming a heating fluid chamber in the bottom thereof; plate means coacting with the wall of said vessel to form an interior, vertically elongated downcorner reservoir and an annularly shaped vapor generation chamber exterior of said reservoir, said plate means extending downwardly to substantially the bottom of said vapor generation chamber but being spaced from said tube sheet to establish fluid communication between said downcorner reservoir and said vapor generation chamber; means for supplying downcorner liquid to said downcorner reservoir; an even number of separate tube bundles each comprising a group of vertically elongated U-tubes having inlet ends and outlet ends attached to said tube sheet in communication with said heating fluid chamber, said U-tubes being arranged in rows lying in parallel planes and having upwardly disposed bends, said tube bundles being located in circumferentially spaced positions about 'said plate means, the inlet ends and the outlet ends of adjacent tube bundles being arranged in adjacent, grouped relation; an axially disposed cylindrical conduit attached at one end to said lower closure head and at the other end to said tube sheet means; divider means arranged Within said heating fluid chamber forming heating fluid 1 inlet and outlet compartments corresponding to the U-tube inlet end and outletend groups; and means communicating with said heating fluid inlet and outlet compartments for circulating heating fluid through said U-tubes.

References Cited by the Examiner UNITED STATES PATENTS 2,774,575 12/1956 Walter 165-158 x FOREIGN PATENTS 521,080 5/1940 Great Britain.

8/1961 Great Britain.

10 CHARLES I. MYHRE, Primary Examiner. 

1. A VAPOR GENERATOR COMPRISING A VERTICAL ELONGATED CYLINDRICAL VESSEL ARRANGED TO OPERATE WITH AN UPPER VAPOR SPACE ABOVE A BODY OF LIQUID THEREIN; A VAPOR OUTLET FROM SAID VAPOR SPACE; PLATE MEANS COACTING WITH THE WALL OF SAID VESSEL TO FORM AN INTERIOR, VERTICALLY ELONGATED DOWNCOMER RESERVOIR AND AN ANNULARLY SHAPED VAPOR GENERATION CHAMBER EXTERIOR OF SAID RESERVOIR, SAID PLATE MEANS EXTENDING DOWNWARDLY TO SUBSTANTIALLY THE BOTTOM OF SAID VAPOR GENERATION CHAMBER BUT BEING SPACED THEREFROM TO ESTABLISH FLUID COMMUNICATION BETWEEN SAID DOWNCOMER RESERVOIR AND SAID VAPOR GENERATION CHAMBER; MEANS FOR SUPPLYING VAPORIZABLE LIQUID TO SAID DOWNCOMER RESERVOIR; AT LEAST THREE SEPARATE TUBE BUNDLES EACH COMPRISING A GROUP OF VERTICALLY ELONGATED U-TUBES ARRANGED IN ROWS LYING IN PARALLEL PLANES, SAID TUBE BUNDLES BEING LOCATED IN CIRCUMFERENTIALLY SPACED POSITIONS ABOUT SAID PLATE MEANS AND SUBSTANTIALLY FILLING SAID VAPOR GENERATION CHAMBER; AND HEATING FLUID INLET AND OUTLET MEANS COMMUNICATING WITH THE TUBES OF SAID TUBE BUNDLES FOR CIRCULATING HEATING FLUID THERETHROUGH. 